Until recently there has persisted a fundamental dichotomy between two main types of telecommunications networks. The first type of telecommunications network, i.e. the telephone network, switches and transports predominantly voice, facsimile, and modulation-demodulation system (modem) traffic. The Public Switched Telephone Network (PSTN) is an example of this type of network. The second type of telecommunications network, i.e. the data network, switches or routes and transports data and video between computers. The Internet is an example of a public data network.
The explosive growth of the Internet as a publication and interactive communication platform has created an electronic environment that is changing the way business is transacted. As the Internet becomes increasingly accessible around the world, voice communications established over the Internet increase exponentially.
Several attempts have been made to facilitate such network-based communications and to provide low cost, flexible solutions. For example, some attempts involve the development and subsequent deployment of Voice over Internet Protocol (VoIP)-based and Session Initiation Protocol (SIP)-based communications systems. VoIP technology enables real-time transmission of voice signals as packetized data over IP networks that employ specific protocols, such as, for example, Transmission Control Protocol (TCP), Real-Time Transport Protocol (RTP), User Datagram Protocol (UDP), and Internet Protocol (IP) suite. SIP technology involves a signaling protocol for Internet conferencing, telephony, instant messaging and other communications. The protocol initiates call setup, routing, authentication, and other feature messages to endpoints within an IP domain. Because Internet-based communications are not fixed to a particular location, these systems provide users with great flexibility as to location and mode of use of such services.
However, one of the major limitations of the current Internet-based communications relates to the inability of such protocols to convey an accurate location of the users. As a result, emergency communications may not be accurately traced and users may be put at risk. In contrast to a regular PSTN, for example, where an area code and a prefix hierarchically specify the location of the calling party, a VoIP user connects to the Internet using a SIP-based communications device capable of supporting VoIP, such as a VoIP telephone, which is identified within the network by an IP address. The IP address is usually assigned by an Internet Service Provider (ISP) and consists of a unique series of numbers. The user of the SIP-based device is identified by a contact address of record (AoR), which is used as part of the SIP protocol to identify both the sending and receiving users of a communication. Because the sending user can use the same AoR to communicate from different locations within the network, the current physical location cannot be ascertained with specificity. Thus, what is needed is a mechanism to provide current location information services to users of VoIP and SIP-based communications technologies.